PORTLAND – The state’s highest court on Friday upheld a decision by election officials to allow Ralph Nader on Maine’s presidential ballot, rejecting a last-ditch appeal by the head of the Maine Democratic Party.

The unanimous decision by the Maine Supreme Judicial Court came 48 hours after justices heard arguments on the appeal by state Democratic Party Chairwoman Dorothy Melanson. The decision puts to an end a weeks-long effort by Democrats to keep Nader off the ballot.

In its ruling, the court said Secretary of State Dan Gwadosky was correct in concluding that Nader and his running mate, Peter Camejo, should be on the ballot.

Nancy Oden of Jonesboro, a spokeswoman for the Nader campaign, said she wasn’t surprised by the decision.

“There are a number of loyal Maine Democrats who are very angry and urged Melanson not to do this to Nader,” Oden said. “But she did it anyway so there is dissension and disarray in the Democratic ranks because of this effort to keep Nader off the ballot.”

In a prepared statement, Melanson said she respected the court’s opinion and urged voters to put their support behind Democrat John Kerry in the race against President George W. Bush.

“No matter the ruling, voters face a clear choice this November,” she said.

The secretary of state’s office in August certified 4,128 voters’ signatures for Nader, 128 more than he needed to get on the ballot.

Melanson challenged the signatures, along with a Brunswick man who joined the challenge at the request of Stopnader.com. They asserted the petition was invalid for including an incorrect first name of an elector on some petition forms, for missing candidate consent forms and for what Melanson said were improper party unenrollment certifications.

After the secretary of state upheld the petitions, Melanson appealed to the Superior Court, which agreed with the secretary of state’s conclusion. Melanson then appealed to the supreme court.

Four years ago, Nader collected 5.7 percent of the vote in Maine as a Green Party presidential candidate.

Democrats fear he could siphon away enough votes from Kerry in Maine to allow President Bush to carry the state on Nov. 2. Recent polls indicate Kerry and Bush are locked in a close race in Maine.

Democrats and Greens have both urged people not to vote for Nader, suggesting a vote for Nader is a vote for Bush.

Nader blasted Democrats for trying to keep him off the state presidential ballot during a campaign visit to the state on Tuesday. “I say to the Democrats in Maine … shame on you,” Nader said.